High frequency semiconductor integrated circuit capable of switching between characteristics

ABSTRACT

A high frequency semiconductor integrated circuit includes a main circuit, a circuit block, a pad, and a wire. The main circuit includes an input terminal, a transistor, transmission lines, a pad, and an output terminal. The circuit block includes a passive circuit and a capacitor. The pad is disposed close to the circuit block. The wire connects the pad to the pad included in the main circuit. In the high frequency semiconductor integrated circuit, the main circuit outputs an input signal input at the input terminal from the output terminal through the transistor, the transmission line, the pad, and another transmission line. As a result, the high frequency semiconductor integrated circuit can realize various performances and can be used in many applications.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high frequency semiconductorintegrated circuit realizing a good high frequency characteristic bychanging a combination of plural circuits according to performance orapplication.

2. Description of the Background Art

Referring to FIG. 22, a prior art high frequency semiconductorintegrated circuit 600 includes a main circuit 610 and a circuit block620.

Main circuit 610 includes an input terminal 6101, a transistor 6102,transmission lines 6103 and 6104, and an output terminal 6105.Transistor 6102 is connected to input terminal 6101 at its gateterminal, to a ground node 7 at its source terminal, and to transmissionline 6103 at its drain terminal. Transistor 6102 is, to be specific, afield effect transistor such as a MOS FET, or a MES FET (MetalSemiconductor Field Effect Transistor), HEMT (High Electron MobilityTransistor) or HET (Heterojunction Bipolar Transistor) made from GaAs.

Transmission lines 6103 and 6104 are connected in series between thedrain terminal of transistor 6102 and output terminal 6105. Transmissionlines 6103 and 6104 are each an interconnect having a predeterminedlength and a predetermined width and formed by patterning in fabricationof high frequency semiconductor integrated circuit 600.

Circuit block 620 includes passive circuits 6201 and 6202 and acapacitor 6203. Passive circuits 6201 and 6202 and capacitor 6203 areconnected in series between a node 6106 of main circuit 610 and groundnode 7. Passive circuits 6201 and 6202, for example, are each configuredsuch that a resistor, a coil and a capacitor, which are passiveelements, are connected in series with or in parallel to each other.That is, passive circuits 6201 and 6202, used together with capacitor6203, each include a circuit of a configuration in which a resistor, acoil and a capacitor are combined in a proper manner such that when aninput signal inputted to input terminal 6101 is outputted from outputterminal 6105 in main circuit 610, output matching, efficiency matching,gain matching and distortion matching can be achieved.

Main circuit 610 receives an input signal having a frequency in therange of microwaves or milliwaves at input terminal 6101 and outputs thereceived input signal from output terminal 6105 through transistor 6102and transmission lines 6103 and 6104.

In a case where passive circuits 6201 and 6202 of circuit block 620 areeach constituted of a passive element optimized for output matching,main circuit 610 performs output matching and outputs an input signalinputted at input terminal 6101 from output terminal 6105. Furthermore,in a case where passive circuits 6201 and 6202 are each constituted of apassive element optimized for efficiency matching, main circuit 610performs efficiency matching and outputs an input signal inputted atinput terminal 6101 from output terminal 6105.

In prior art high frequency semiconductor integrated circuit 600,however, circuit block 620 is connected to node 6106 of main circuit610; therefore, when only main circuit 610 is desired to be used, orwhen a high frequency semiconductor integrated circuit having adifferent performance is requested, a problem arises since separatecircuit patterns are required. That is, when passive circuits 6201 and6202, each constituted of a passive element optimized for outputmatching, are incorporated into circuit block 620, only main circuit 610cannot be used and further, high frequency semiconductor integratedcircuit 600 cannot be differently used as a high frequency semiconductorintegrated circuit for achieving efficiency matching.

Furthermore, once a circuit pattern is formed on a semiconductorsubstrate, a circuit block cannot be adjusted if variations occur inperformance of an active element, leading to another problem of decreasein product yield of a high frequency semiconductor integrated circuit.

SUMMARY OF THE INVENTION

It is, accordingly, an object of the present invention to provide a highfrequency semiconductor integrated circuit capable of switching betweencharacteristics thereof.

It is another object of the present invention to provide a highfrequency semiconductor integrated circuit capable of performing circuitadjustment for improving a high frequency characteristic.

According to the present invention, a high frequency semiconductorintegrated circuit includes: a main circuit having an active element anda first pad therein; a circuit block constituted of a passive element; asecond pad connected to the circuit block; and a wire to connect thefirst pad to the second pad.

It is preferable that the main circuit includes the active element andthe first pad between an input terminal and an output terminal.

It is preferable that the circuit block includes a passive element whoseimpedance decreases with increase in frequency of an input signalinputted at the input terminal.

It is preferable that the circuit block includes an interconnectconnected to the second pad and the sum of a length of the wire and alength of the interconnect is equal to one-fourth of a wavelength of ahigh frequency signal inputted at the input terminal.

Furthermore, according to the present invention, a high frequencysemiconductor integrated circuit includes: a main circuit having anactive element and a main pad therein; plural circuit blocks eachconstituted of a passive element; plural connection pads providedcorrespondingly to the respective plural circuit blocks; and a wire forconnecting the main pad to one of the plural connection pads.

It is preferable that the main circuit includes the active element andthe main pad between an input terminal and an output terminal.

It is preferable that the plural circuit blocks include a first circuitblock for adjusting an impedance of the main circuit to be a firstimpedance, a second circuit block for adjusting the impedance of themain circuit to be a second impedance, and a third circuit block foradjusting the impedance of the main circuit to be a third impedance.

It is preferable that the first circuit block is constituted of a firstcapacitor having a first capacity, and connected to a ground node at oneend thereof and a first connection pad at the other end thereof, thesecond circuit block is constituted of a second capacitor having asecond capacity, and connected to the ground node at one end thereof anda second connection pad at the other end thereof and the third circuitblock is constituted of a third capacitor having a third capacity, andconnected to the ground node at one end thereof and a third connectionpad at the other end thereof.

Furthermore, according to the present invention, a high frequencysemiconductor integrated circuit includes a first high frequencysemiconductor integrated circuit, a second high frequency integratedcircuit, and a main wire for connecting the first high frequencysemiconductor integrated circuit to the second high frequencysemiconductor integrated circuit.

It is preferable that the first high frequency semiconductor integratedcircuit includes a main circuit having an active element, and a circuitblock having a passive element, and the second high frequencysemiconductor integrated circuit includes only a main circuit having anactive element.

It is preferable that the second high frequency semiconductor integratedcircuit includes a first main circuit having a first active element anda first pad, and the first high frequency semiconductor integratedcircuit includes a circuit block having a passive element, a second padconnected to the circuit block, a second main circuit having a third padfor connecting the first and second pads with each other, and a secondactive element, and a wire for connecting the second pad to the thirdpad, wherein the main wire connects the first pad to the third pad.

It is preferable that the first main circuit further includes aninterconnect connected to the first pad at one end thereof and the firstactive element at the other end thereof, and an output terminalconnected to the first active element; and the second main circuitfurther includes an interconnect connected to the third pad at one endthereof and the second active element at the other end thereof, and aninput terminal connected to the second active element.

It is preferable that the circuit block includes a passive element formatching an impedance of the first main circuit to an impedance of thesecond main circuit.

It is preferable that the first high frequency semiconductor integratedcircuit includes only a main circuit having an active element and thesecond high frequency semiconductor integrated circuit includes only acircuit block having a passive element.

It is preferable that the first high frequency semiconductor integratedcircuit includes only a main circuit having an active element and a mainpad, and the second high frequency semiconductor integrated circuitincludes plural circuit blocks each having a passive element and pluralconnection pads provided correspondingly to the respective pluralcircuit blocks, wherein the main wire connects the main pad to one ofthe plural connection pads.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a high frequency semiconductor integratedcircuit according a first embodiment;

FIG. 2 is a plan view of a transmission line shown in FIG. 1;

FIG. 3 is a plan view of interconnection constituting a passive circuitincluded in a circuit block shown in FIG. 1;

FIG. 4 is a plan view showing another example of the passive circuitincluded in a circuit block shown in FIG. 1;

FIG. 5 is a block diagram and a circuit diagram of a high frequencysemiconductor integrated circuit according to a second embodiment;

FIG. 6 is a circuit diagram of a circuit block shown in FIG. 5;

FIG. 7 is a circuit diagram of another circuit block shown in FIG. 5;

FIG. 8 is a circuit diagram of yet another circuit block shown in FIG.5;

FIG. 9 is a Smith chart;

FIG. 10 is a Smith chart containing constant-output circles;

FIG. 11 is a Smith chart containing constant-efficiency circles;

FIG. 12 is a block diagram and a circuit diagram of a high frequencysemiconductor integrated circuit according to a third embodiment;

FIGS. 13A and 13B are plan views of transmission lines shown in FIG. 12;

FIG. 14 is a plan view showing an example of a circuit block shown inFIG. 12,

FIG. 15 is a block diagram and a circuit diagram of a high frequencysemiconductor integrated circuit according to a fourth embodiment;

FIG. 16 is a circuit diagram of a circuit block shown in FIG. 15;

FIG. 17 is a circuit diagram of another circuit block shown in FIG. 15;

FIG. 18 is a circuit diagram of yet another circuit block shown in FIG.15;

FIG. 19 is a circuit diagram of still another circuit block shown inFIG. 15;

FIG. 20 is a block diagram and a circuit diagram of another highfrequency semiconductor integrated circuit according to the fourthembodiment;

FIG. 21 is a plan view showing a specific example of one of two highfrequency semiconductor integrated circuits shown in FIG. 20; and

FIG. 22 is a circuit diagram of a prior art high frequency semiconductorintegrated circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed description will be given of embodiments of the presentinvention referring to the accompanying drawings. Note that the samesymbols are attached to the same or corresponding constituents in thefigures and description thereof is not repeated.

First Embodiment

Referring to a FIG. 1, a high frequency semiconductor integrated circuit100 according to the first embodiment includes a main circuit 10, acircuit block 20, a pad 30, and a wire 40. Main circuit 10, circuitblock 20 and pad 30 are fabricated on one semiconductor substrate.

Main circuit 10 includes an input terminal 1, a transistor 2,transmission lines 3 and 5, a pad 4, and an output terminal 6.Transistor 2 is connected to input terminal 1 at the gate terminalthereof, a ground node 7 at the source terminal thereof and transmissionline 3 at the drain terminal thereof. Transmission line 3 is disposedbetween the drain terminal of transistor 2 and pad 4. Transmission line5 is disposed between pad 4 and the output terminal 6.

Circuit block 20 includes a passive circuit 21 and a capacitor 22.Passive circuit 21 and capacitor 22 are connected in series between pad30 and ground node 7. Pad 30 is disposed close to circuit block 20. Wire40 connects pad 30 to pad 4 included in main circuit 10. Therefore,circuit block 20 is connected in parallel to a circuit extending frominput terminal 1 to output terminal 6.

Referring to FIG. 2, transmission lines 3 and 5 are constituted of aninterconnect 31 made from gold (Au). Interconnect 31 has a length L1 anda width W1. Therefore, transmission lines 3 and 5 each has an impedancecharacteristic having a parallel resonance point for a frequency of aninput signal.

Referring to FIG. 3, passive circuit 21 is constituted of a coil 210 anda capacitor 211, for example. Coil 210 and capacitor 211 are connectedin parallel to each other. Therefore, circuit block 20 has one seriesresonance point and one parallel resonance point for a frequency of aninput signal and an impedance characteristic approaching zero at thefinal stage. If a capacity of capacitor 22 is C1 [F], a capacity ofcapacitor 211 is C2 [F] and a frequency of the input signal is f [Hz] bydefinition, an impedance of capacitor 22 is determined by 1/(2πfC1) andan impedance of capacitor 211 is determined by 1/(2πfC2); therefore, theimpedance of each of capacitors 22 and 211 approaches zero with increasein frequency f. Hence, an impedance of circuit block 20 approaches zeroas a frequency of the input signal increases. Note that a frequency f ofthe input signal falls in the range of microwaves or milliwaves.

As described above, main circuit 10 is one including an active elementand circuit block 20 is one constituted of a passive element.

Referring again to FIG. 1, in main circuit 10, an input signal inputtedat input terminal 1 is transmitted to pad 4 through transistor 2 andtransmission line 3. The input signal is further transmitted from pad 4to transmission line 5 and to wire 40. The input signal outputted totransmission line 5 is transmitted through transmission line 5 andoutputted from output terminal 6.

On the other hand, the input signal transmitted to wire 40 istransmitted through wire 40 and inputted to circuit block 20 through pad30. In this case, wire 40 functions on the input signal as an equivalentcircuit constructed of parallel circuits each constituted of a coil anda capacitor connected at plural stages. Hence, an impedance of wire 40approaches zero with a frequency of the input signal being high. As aresult, wire 40 and circuit block 20 combined is in an open state as aneffect exerted on pad 4 and an input signal inputted at input terminal 1is transmitted through main circuit 10 with decreased transmissionleakage and outputted from output terminal 6. In this case, main circuit10 does not output any signal having a frequency other than a frequencyof the input signal.

Referring to FIG. 4, circuit block 20 may also be constituted of aninterconnect 220. Interconnect 220 is formed when circuit block 20 isfabricated and has dimensions of a length L2 and a width W2. In thiscase, if a length of wire 40 is Lw and a wavelength of the input signalis λ, length Lw of wire 40 and length L2 of interconnect 220 aredetermined such that λ/4=Lw+L2. If λ/4=Lw+L2, an amplitude of an inputsignal transmitted through wire 40 and pad 30 to interconnect 220 frompad 4 is reduced to zero at one end 221 of interconnect 220. That is, acircuit constituted of wire 40 and interconnect 220 becomes a shortedcircuit. Therefore, wire 40 and circuit block 20 combined enters an openstate as an effect exerted on pad 4 and an input signal inputted atinput terminal 1 is transmitted through main circuit 10 with decreasedtransmission leakage and outputted from output terminal 6. In this case,main circuit 10 does not output a signal of any frequency other than afrequency of the input signal.

As described above, in a case where a circuit configured such thatpassive circuit 21 and capacitor 22 as shown in FIG. 3 are connected inseries with each other as circuit block 20, or alternatively, in a casewhere interconnect 220 shown in FIG. 4 is used as circuit block 20,there can be fabricated high frequency semiconductor integrated circuit100 capable of transmitting an input signal through main circuit 10preventing transmission leakage of the input signal from occurring. Whenonly main circuit 10 of high frequency semiconductor integrated circuit100 is desired to be used, wire 40 has only to be disconnected and nonecessity arises for separately fabricating a high frequencysemiconductor integrated circuit constituted of main circuit 10 only. Insuch a way, a high frequency semiconductor integrated circuit capable oftransmitting an input signal preventing transmission leakage fromoccurring by connecting circuit block 20 to main circuit 10 with wire 40can also be functioned as a high frequency semiconductor integratedcircuit constituted of main circuit 10 only. The present inventionfeatures that wire 40 functions as one circuit transmitting an inputsignal of high frequency as described above.

According to the first embodiment, since a high frequency semiconductorintegrated circuit includes a main circuit and a circuit block connectedby a wire therebetween, there can be realized a high frequencysemiconductor integrated circuit having plural performances according tothe presence or absence of wire connection.

Second Embodiment

Referring to FIG. 5, a high frequency semiconductor integrated circuit200 according to the second embodiment includes: main circuit 10; wire40; circuit blocks 50, 60 and 70; and pads 55, 65 and 75. Main circuit10 is as described above. Pads 55, 65 and 75 are providedcorrespondingly to respective circuit blocks 50, 60 and 70. Wire 40connects pad 4 included in main circuit 10 to one of pads 55, 65 and 75.

Referring to FIG. 6, circuit block 50 includes a capacitor 51. Oneelectrode of capacitor 51 is connected to ground node 7 and the otherelectrode of capacitor 51 is connected to pad 55. Capacitor 51 has acapacitance C3 [F].

Referring to FIG. 7, circuit block 60 includes capacitor 61. Oneelectrode of capacitor 61 is connected to ground node 7 and the otherelectrode thereof is connected to pad 65. Capacitor 61 has a capacitanceC4 [F].

Referring to FIG. 8, circuit block 70 includes a capacitor 71. Oneelectrode of capacitor 71 is connected to ground node 7 and the otherelectrode thereof is connected to pad 75. Capacitor 71 has a capacitanceC5 [F].

Referring again to FIG. 5, since wire 40 functions on an input signal asan equivalent circuit constructed of parallel circuits each constitutedof a coil and a capacitor connected at plural stages as described above,there can be realized a high frequency semiconductor integrated circuithaving a different performance according to which of pads 55, 65 and 75wire 40 is connected to. When an output impedance of a transistor has animpedance shown in FIG. 9, there can be realized a high frequencysemiconductor integrated circuit having an impedance shown in FIG. 10 byconnecting pad 55 to pad 4 of main circuit 10 with wire 40. In thiscase, capacitance C3 of capacitor 51 included in circuit block 50 isdetermined such that reactance of wire 40 and circuit block 50 combinedbecomes zero. That is, capacitance C3 of capacitor 51 is determined suchthat an impedance of wire 40 and circuit block 50 combined is located ona real axis of the Smith chart shown in FIG. 10. Circuit block 50 isconnected to main circuit 10 by wire 40 and another circuit blockconstituting of an impedance converter is disposed at output terminal 6side with respect to pad 4, whereby high frequency semiconductorintegrated circuit 200 can function as a high frequency semiconductorintegrated circuit having been subjected to gain matching.

Furthermore, by connecting circuit block 60 to main circuit 10 with wire40, there can be realized a high frequency semiconductor integratedcircuit having an impedance at point A on the Smith chart shown in FIG.11. In this case, capacitance C4 of capacitor 61 included in circuitblock 60 is determined such that an impedance of wire 40 and circuitblock 60 combined is located at point A above the real axis.

Still furthermore, by connecting circuit block 70 to main circuit 10with wire 40, there can be realized a high frequency semiconductorintegrated circuit having an impedance of point B on the Smith chartshown in FIG. 11. In this case, capacitance C5 of capacitor 71 includedin circuit block 70 is determined such that an impedance of wire 40 andcircuit block 70 combined is located at point B above the real axis.

A circle depicted on the Smith chart shown in FIG. 10 is aconstant-output circle, which is obtained by changing capacitance C3 ofcapacitor 51 included in circuit block 50. Therefore, by changingcapacitance C3 of capacitor 51 included in circuit block 50, there canbe realized a high frequency semiconductor integrated circuit having animpedance thereof moving on a constant-output circle shown in FIG. 10.On the other hand, a circle on the Smith chart shown in FIG. 11 shows aconstant-efficiency circle and a constant-efficiency circle can beobtained by changing capacitance C4 and C5 of capacitors 61 and 71included in respective circuit blocks 60 and 70. Therefore, by changingcapacitance C4 and C5 of capacitors 61 and 71 included in respectivecircuit blocks 60 and 70, there can be realized a high frequencysemiconductor integrated circuit having an impedance moving on aconstant-efficiency circle shown in FIG. 11.

As described above, main circuit 10 is a circuit including an activeelement and circuit blocks 50, 60 and 70 are each a circuit constitutedof a passive element.

High frequency semiconductor integrated circuit 200 can also functionnot only as one including only main circuit 10 by disconnecting wire 40,but as one having each of various kinds of performances described aboveby connecting one of circuit blocks 50, 60 and 70 to main circuit 10.

In the above description, although circuit blocks 50, 60 and 70 are eachhandled as one including one capacitor, circuit blocks 50, 60 and 70 mayinclude plural capacitors respectively, any of which can be selected.With such configurations, when there occur variations in characteristicof an active element (a transistor) included in main circuit 10, thevariations in characteristic of the active element can be adjustablyremoved by selecting one of capacitors included in respective circuitblocks 50, 60 and 70. In this case, as a transistor, there can beconsidered a field effect transistor such as a MOS transistor, or MESFET, HEMT or HBT using GaAs.

A circuit block may be disposed not only at the output side of atransistor, but also at the input side or at both of the input side andoutput side thereof.

Although in the above description, one circuit block is connected tomain circuit 10 by wire 40, plural circuit blocks are selected andconnected in series or in parallel.

According to the second embodiment, since a high frequency semiconductorintegrated circuit includes: a main circuit; and plural circuit blocksthat can be connected to the main circuit by a wire, there can befabricated a high frequency semiconductor integrated circuit capable ofrealizing plural performances by selecting a circuit block to beconnected to the main circuit with wire.

Third Embodiment

Referring to FIG. 12, a high frequency semiconductor integrated circuit300 according to the third embodiment includes a high frequencysemiconductor integrated circuit 310, a high frequency semiconductorintegrated circuit 320, and a wire 330.

High frequency semiconductor integrated circuit 310 includes a maincircuit 301, a circuit block 302, a pad 303, and a wire 304. Maincircuit 301 includes an input terminal 3010, a transistor 3011, atransmission line 3012, and a pad 3013. Transistor 3011 is connected toinput terminal 3010 at the gate terminal thereof and ground node 7 atthe source terminal thereof and transmission line 3012 at the drainterminal thereof. Transmission line 3012 is connected between the drainterminal of transistor 3011 and pad 3013.

Pad 303 is disposed close to circuit block 302. Wire 304 connects pad303 to pad 3013 of main circuit 301 to connect circuit block 302 to maincircuit 301.

High frequency semiconductor integrated circuit 320 includes a pad 3200,a transmission line 3201, a transistor 3202, and an output terminal3203. Transmission line 3201 is connected between pad 3200 and the gateterminal of transistor 3202. Transistor 3202 is connected totransmission line 3201 at the gate terminal thereof, ground terminal 7at the source terminal thereof and output terminal 3203 at the drainterminal thereof. That is, high frequency semiconductor integratedcircuit 320 is one including an active element similar to main circuit301 of high frequency semiconductor integrated circuit 310.

Wire 330 connects pad 3013 included in main circuit 301 of highfrequency semiconductor integrated circuit 310 to pad 3200 of highfrequency semiconductor integrated circuit 320.

Referring to FIG. 13A, transmission line 3012 is constituted of aninterconnect 3014. Interconnect 3014 has dimensions of a length L3 and awidth W3. Furthermore, referring to FIG. 13B, transmission line 3201 isconstituted of an interconnect 3204. Interconnect 3204 has dimensions ofa length L4 and a width W4. Therefore, main circuit 301 of highfrequency semiconductor integrated circuit 310 has an impedancedifferent from an impedance of high frequency semiconductor integratedcircuit 320.

Referring to FIG. 14, circuit block 302 is constituted of aninterconnect 3020. Interconnect 3020 has dimensions of a length L5 and awidth W5. When a length of wire 304 is Lw and a wavelength of an inputsignal is λ, length L5 of interconnect 3020 and length Lw of wire 304are determined such that λ/4=Lw+L5 and an impedance of main circuit 301matches to an impedance of high frequency semiconductor integratedcircuit 320. In this case, an amplitude of an input signal becomes zeroat one end 3021 of interconnect 3020 to enter a shorted state.Therefore, an impedance of wire 304 and circuit block 302 combinedbecomes zero as an effect exerted on pad 3013. Then, an input signalinputted at input terminal 3010 is transmitted to pad 3013 throughtransistor 3011 and transmission line 3012 and further onto wires 304and 330 by pad 3013. Since an impedance of wire 304 and circuit block302 combined is zero and an impedance of main circuit 301 has matched tohigh frequency semiconductor integrated circuit 320 in impedance, theinput signal is transmitted to pad 3200 through wire 330 without a loss.Then, the input signal is outputted from output terminal 3203 throughtransmission line 3201 and transistor 3202.

As described above, main circuit 301 is a circuit including an activeelement and circuit block 302 is a circuit constituted of a passiveelement. Furthermore, high frequency semiconductor integrated circuit320 is constituted of a circuit including an active element similar tomain circuit 301.

In high frequency semiconductor integrated circuit 300, circuit block302 performs a function to cause an impedance of main circuit 301 tomatch to an impedance of high frequency semiconductor integral circuit320. Furthermore, pad 3013 performs a function to connect circuit block302 to main circuit 301 and a function to connect high frequencysemiconductor integrated circuit 320 to high frequency semiconductorintegrated circuit 310. In such way, by not only connecting a circuitblock to a main circuit but also connecting integrated circuits formedon respective different semiconductor substrates to each other, a chipsize of high frequency semiconductor integrated circuit 300 can bereduced.

Furthermore, by disconnecting wire 330, high frequency semiconductorintegrated circuit 310 and high frequency semiconductor integratedcircuit 320 can be operated independently of each other. Moreover, inhigh frequency semiconductor integrated circuit 310, by disconnectingwire 304, high frequency semiconductor integrated circuit 300 can beoperated as a high frequency semiconductor integrated circuit includingmain circuit 301 only.

According to the third embodiment, a high frequency semiconductorintegrated circuit is constructed by connecting two high frequencysemiconductor integrated circuits with a wire and a pad for use inconnecting a circuit block to a main circuit with a wire in one highfrequency semiconductor integrated circuit is further used in connectingtwo high frequency semiconductor integrated circuits therebetween,thereby enabling a chip size of a high frequency semiconductorintegrated circuit to be reduced.

Fourth Embodiment

Referring to FIG. 15, a high frequency semiconductor integrated circuit400 according to the fourth embodiment includes a high frequencysemiconductor integrated circuit 410, a high frequency semiconductorintegrated circuit 420, and a wire 430. High frequency semiconductorintegrated circuit 410 includes an input terminal 4101, a transistor4102, a transmission line 4103, and a pad 4104. Transistor 4102 isconnected to input terminal 4101 at the gate terminal thereof, groundterminal 7 at the source terminal thereof and transmission line 4103 atthe drain terminal thereof Transmission line 4103 is connected betweenthe drain terminal of transistor 4102 and pad 4104. Used as transmissionline 4103, for example, is interconnect 3014 shown in FIG. 13A.

High frequency semiconductor integrated circuit 420 includes circuitblocks 421 to 424, and pads 425 to 428. Pads 425 to 428 are providedcorrespondingly to respective circuit blocks 421 to 424.

Wire 430 connects pad 4104 of high frequency semiconductor integratedcircuit 410 to one of pads 425 to 428 of high frequency semiconductorcircuit 420.

Referring to FIG. 16, circuit block 421 includes a pad 4211, atransmission line 4212, a coil 4213, and a capacitor 4214. Transmissionline 4212 is connected between pad 4211 and pad 425. Used astransmission line 4212 is an interconnect having a predetermined lengthand a predetermined width. Coil 4213 and capacitor 4214 are connected inparallel between a node 4215 and ground node 7. When wire 430 isconnected to pad 425, an input signal is transmitted to circuit block421 through pad 425. Since a parallel circuit constituted of coil 4213and capacitor 4214 acts on a high frequency signal as an impedance closeto zero, the input signal is transmitted through transmission line 4212with almost no loss to be caused by the parallel circuit and outputtedfrom pad 4211. A signal having a frequency other than a frequency of theinput signal is lost in the parallel circuit and the input signal istransmitted through transmission line 4212 and outputted from pad 4211.

Referring to FIG. 17, circuit block 422 includes a pad 4221, atransmission line 4222, and a capacitor 4223. Transmission line 4222 isconnected between pad 4221 and pad 426. Transmission line 4222 isconstituted of an interconnect having a predetermined length and apredetermined width. Capacitor 4223 is connected between a node 4224 andground node 7. Since capacitor 4223 does not act on a high frequencysignal as an impedance, a circuit constituted of node 4224, capacitor4223 and ground node 7 becomes a shorted circuit. When wire 430 isconnected to pad 426, high frequency semiconductor integrated circuit400 becomes the same circuit as high frequency semiconductor integratedcircuit 200 in which wire 40 is connected to pad 55. Therefore, when pad4221 is used as an output terminal, high frequency semiconductorintegrated circuit 400 functions as a high frequency semiconductorintegrated circuit having an impedance shown in FIG. 10.

Referring to FIG. 18, circuit block 423 includes a pad 4231, atransmission line 4232, and a capacitor 4233. Transmission line 4232 isconnected between pad 4231 and pad 427. Transmission line 4232 isconstituted of an interconnect having a predetermined length and apredetermined width. Capacitor 4233 is connected between a node 4234 andground node 7. Since capacitor 4233 does not act on a high frequencysignal as an impedance, a circuit constituted of node 4234, capacitor4233 and ground node 7 becomes a shorted circuit. When wire 430 isconnected to pad 427, high frequency semiconductor integrated circuit400 becomes the same circuit as high frequency semiconductor circuit 200in which wire 40 is connected to pad 65. Therefore, when pad 4231 isused as an output terminal, high frequency semiconductor integratedcircuit 400 functions as a high frequency semiconductor integratedcircuit having an impedance of point A shown in FIG. 11.

Referring to FIG. 19, circuit block 424 includes a pad 4241, atransmission line 4242, and a capacitor 4243. Transmission line 4242 isconnected between pad 4241 and pad 428. Transmission line 4242 isconstituted of an interconnect having a predetermined length and apredetermined width. Capacitor 4243 is connected between a node 4244 andground node 7. Since capacitor 4243 does not act on a high frequencysignal as an impedance, a circuit constituted of node 4244, capacitor4243 and ground node 7 becomes a shorted circuit. When wire 430 isconnected to pad 428, high frequency semiconductor integrated circuit400 becomes the same circuit as high frequency semiconductor integratedcircuit 200 in which wire 40 is connected to pad 75. Therefore, when pad4241 is used as an output terminal, high frequency semiconductorintegrated circuit 400 functions as a high frequency semiconductorintegrated circuit having an impedance of point B shown in FIG. 11.

Referring again to FIG. 15, by connecting pad 4104 to one of pads 425 to428 of high frequency semiconductor integrated circuit 420 with wire430, high frequency semiconductor integrated circuit 400 can function asa high frequency semiconductor integrated circuit having various kindsof performances.

In high frequency semiconductor integrated circuit 400, high frequencysemiconductor integrated circuit 410 includes a main circuit only, highfrequency semiconductor integrated circuit 420 includes a circuit blockonly. In such a manner, by fabricating a main circuit and a circuitblock separately on semiconductor substrates, the number of chips in asemiconductor substrate on which a main circuit is fabricated can beincreased.

A high frequency semiconductor integrated circuit according to thefourth embodiment may be a high frequency semiconductor integratedcircuit 500 shown in FIG. 20. High frequency semiconductor integratedcircuit 500 includes high frequency semiconductor integrated circuit410, wire 430, and a high frequency semiconductor integrated circuit440. High frequency semiconductor integrated circuit 410 is as describedabove.

High frequency semiconductor integrated circuit 440 includes circuitblocks 431 to 435, pad 441 to 446, and wire 451 to 453. Pads 441 to 445are provided correspondingly to respective circuit blocks 431 to 435.

Circuit block 435 includes an interconnect 4351, and pads 4352 to 4355.Pads 445 and 446 are connected to interconnect 4351 of circuit block435. Wire 451 connects pad 441 to pad 4352 of circuit block 435. Wire452 connects pad 443 to pad 4353 of circuit block 435. Wire 453 connectspad 444 to pad 4355 of circuit block 435.

Wire 430 connects pad 4104 of high frequency semiconductor integratedcircuit 410 to pad 445 of high frequency semiconductor integratedcircuit 440. Thereby, an input signal inputted at input terminal 4101 ofhigh frequency semiconductor integrated circuit 410 is inputted to pad445 of high frequency semiconductor integrated circuit 440 throughtransistor 4102, transmission line 4103, pad 4104 and wire 430. Then,the input signal is propagated through interconnect 4351 of circuitblock 435 and outputted from pad 446.

Referring to FIG. 21, detailed description will be given of highfrequency semiconductor integrated circuit 440. Circuit block 431includes: an interconnect 4310; and blocks 4311 to 4313. Interconnect4310 is connected to pad 441 at one end thereof. Interconnect 4310 ismade from metal having a length L6 and a width W6. A block 4311 isdisposed spaced apart from the other end of wire 4310 by a predetermineddistance. A block 4312 is disposed spaced apart from block 4311 by apredetermined distance. A block 4313 is disposed spaced apart from block4312 by a predetermined distance. Blocks 4311 to 4313 respectively havethe same width W6 as that of interconnect 4310 and made from the samemetal as is interconnect 4310. Block 4311 can be connected tointerconnect 4310 with a wire, block 4312 can be connected to block 4311with a wire and block 4313 can be connected to block 4312 with a wire.

Length L6 of interconnect 4310 is determined such that λ/4=L6, where awave length of an input signal is λ. Thereby, the input signal has themaximum amplitude (open) at the other end 4314 of interconnect 4310 andcircuit block 431 acts on the input signal as a shorted circuit. Blocks4311 to 4313 are used for adjustment of length L6 of interconnect 4310such that interconnect 4310 functions as a shorted circuit when afrequency of the input signal changes.

Circuit block 433 includes an interconnect 4330, and blocks 4331 to4333. Interconnect 4330 is connected to pad 443 at one end thereof.Interconnect 4330 is made from metal having a length L7 and a width W7.Block 4331 is disposed spaced apart from the other end of interconnect4330 by a predetermined distance. Block 4332 is disposed apart fromblock 4331 by a predetermined distance. Block 4333 is disposed apartfrom block 4332 by a predetermined distance. Blocks 4331 to 4333respectively have the same width W7 as does interconnect 4330 and madefrom the same metal as is interconnect 4330. Block 4331 can be connectedto interconnect 4330 with a wire, block 4332 can be connected to block4331 with a wire and block 4333 can be connected to block 4332 with awire.

Length L7 of interconnect 4330 is determined such that λ/4=L7, where awave length of an input signal is λ. Thereby, the input signal has themaximum amplitude (open) at the other end 4334 of interconnect 4330 andcircuit block 433 acts on the input signal as a shorted circuit. Blocks4331 to 4333 are used for adjustment of length L7 of interconnect 4330such that interconnect 4330 functions as a shorted circuit when afrequency of the input signal changes.

Circuit block 432 includes an interconnect 4321, a block 4322, and awire 4323. Interconnect 4321 is connected to pad 442 at one end thereofBlock 4322 is disposed spaced apart from the other end of interconnect4321 by a predetermined distance and can be connected to interconnect4321 with wire 4323. A length of interconnect 4321 is determined suchthat an amplitude of a signal becomes zero at the other end. That is,circuit block 432 acts on the input signal as a shorted circuit.

Circuit block 434 includes interconnects 4341 and 4342, a block 4343,and wires 4344 and 4345. Interconnect 4341 is connected to pad 444 atone end thereof. One end of interconnect 4342 is disposed spaced apartfrom the other end of interconnect 4341 by a predetermined distance.Interconnect 4342 is connected to interconnect 4341 with wire 4344.Block 4343 is disposed spaced apart from the other end of interconnect4342 by a predetermined distance and connected to interconnect 4342 withwire 4345. Circuit block 434 acts on an input signal as a circuitconfigured such that a coil and a capacitor are connected in series.

Referring again to FIG. 20, high frequency semiconductor integratedcircuit 410 propagates an input signal through transistor 4102,transmission line 4103 and pad 4104 and outputs the input signal to highfrequency semiconductor integrated circuit 440 through wire 430 when theinput signal is inputted at input terminal 4101. Then, high frequencysemiconductor integrated circuit 440 propagates the input signalinputted from pad 445 through interconnect 4351 of circuit block 435 andoutputs the input signal from pad 446. In this case, since circuitblocks 431 and 433 respectively act on the input signal as a shortedcircuit, the input signal is outputted from pad 446 after receiving animpedance determined by interconnect 4351 and circuit block 434. In thiscase, the input signal suffers small loss from circuit blocks 431 and433.

In high frequency semiconductor integrated circuit 440, by connectingpad 442 to pad 4354 of circuit block 435 with a wire, a propagationcharacteristic of an input signal can be varied.

According to the fourth embodiment, since a high frequency semiconductorintegrated circuit can be fabricated by connecting with a wire, a highfrequency semiconductor integrated circuit including only a main circuitto a high frequency semiconductor integrated circuit including only acircuit block, the number of chips formed on a semiconductor substrateon which a main circuit is fabricated can be increased.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A semiconductor integrated circuit comprising: a main circuit havingan active element and a first pad; a circuit block including a passiveelement; a second pad connected to said circuit block; and a wireconnecting said first pad to said second pad, wherein said main circuitincludes an input terminal and an output terminal and said activeelement and said first pad are located between said input terminal andsaid output terminal, said circuit block includes an interconnectconnected to said second pad, and said wire and said interconnect havelengths totaling one-fourth of a wavelength of a signal input to saidinput terminal.